The regulation of PRL secretion in various hyperprolactinemic states will be evaluated with a 24 hr profile, dopamine infusion, TRH stim and metachlopramide stim testing. Emphasis will be placed on patients hypersecreting 150,000K PRL. Column chromatography and NB2 bioassay will be used to evaluate various molecular weight PRL release. Frequency and natura) history of macroprolactinemia will be established.